Morphology and temperature dependence of the thermal conductivity of nanoporous SiGe.

Using molecular dynamics simulations, we show that the thermal conductivity (κ) of Si(0.5)Ge(0.5) can be reduced by more than one order of magnitude by etching nanometer-sized holes in the material, and it becomes almost constant as a function of temperature between 300 and 1100 K for samples with 1 nm wide pores. In nanoporous SiGe, thermal conduction is largely determined by mass disorder and boundary scattering, and thus the dependence of κ on pore distance and on structural, atomistic disorder is much weaker than in the case of nanoporous Si. This indicates that one may minimize κ of the alloy with less stringent morphological constraints than for pure Si.